Public and private lighting account for a relevant share of the overall electric power consumption worldwide. The pressing need of reducing the carbon dioxide emissions as well as of lowering the lumenâ€¢hour price tag has fostered the search for alternative lighting technologies to substitute for the incandescent and gas-discharge based lamps. The most successful approach to date, solid-state lighting, is already finding its way into the public lighting market, very often helped by substantial public investments and support. LED-based sources have distinct advantages: under controlled conditions their efficacy equals or surpasses that of conventional solutions, their small source size allows for an efficient collimation of the lightbeam (delivering the photons where they are actually needed and reducing lightspill on the surrounding areas), and they can be switched and/or dimmed on demand at very high rates, thus allowing for a tailored schedule of lighting. However, energy savings and carbon dioxide reduction are not the only crucial issues faced by present day lighting. A growing body of research has shown the significance of the spectral composition of light when it comes to assess the detrimental effects of artificial light-at-night (ALAN). The potential ALAN blueshift associated to the deployment of LED-based lighting systems has raised sensible concerns about its scientific, cultural, ecological and public health consequences, which can be further amplified if an increased light consumption is produced due to the rebound effect. This contribution addresses some of the challenges that these issues pose to the Optics and Photonics community.

In this work, we propose an approach to estimating the amount of light wasted by being sent towards the upper hemisphere from urban areas. This is a source of light pollution. The approach is based on a predictive model that provides the fraction of light directed skywards in terms of a small set of identified explanatory variables that characterise the urban landscape and its light sources. The model, built via the statistical analysis of a wide sample of basic urban scenarios to compute accurately the amount of light wasted at each of them, establishes an optimal linear regression function that relates the fraction of wasted flux to relevant variables like the kind of luminaires, the street fill factor, the street width, the building and luminaire heights and the walls and pavement reflectances. We applied this model to evaluate the changes in emissions produced at two urban nuclei in the Deltebre municipality of Catalonia. The results agree reasonably well with those deduced from the radiance measurements made with the VIIRS instrument onboard the Suomi-NPP Earth orbiting satellite.

The Zernike power spectra of the all-sky night brightness distributions of clear and cloudy nights are computed using a modal projection approach. The results obtained in the B, V and R Johnson-Cousins' photometric bands during a one-year campaign of observations at a light-polluted urban site show that these spectra can be described by simple power laws with exponents close to -3 for clear nights and -2 for cloudy ones. The second-moment matrices of the Zernike coefficients show relevant correlations between modes. The multiplicative role of the cloud cover, that contributes to a significant increase of the brightness of the urban night sky in comparison with the values obtained in clear nights, is described in the Zernike space.

Reducing and controlling the pest population using light traps is an age old practice in our crop sector. Though there are several models and designs are available but we would plan to develop something that could be solar powered trap with collecting net and not dependent on any other source like wind power, mechanical power, fuel & electricity. This device operates automatically, turning on the light during light fails i.e., 6 P.M and turns off before sunrises i.e., 6A.M. Most of the damage causing insects are active only during that time. Installing one light trap in an acre attracts at least more than 1000 adult pests for a day. The insects attract solar light trap model had been tested in our field crops like vegetables, paddy, and sugarcane, fruit crops like mango, pomegranate, guava, coconut and tea, coffee and jasmine crops across India. In this study we examine the relationship between the Lunar Phases and the efficiency of light traps in catching pests in the month of March and April at Madanapalli, Chittor, Andhra Pradesh. The lunar phase depending on the polarized moonlight and the relative catch follow the collecting distance. The collecting distance ranged and averaged in the phase angle divisions. The study demonstrated for the first time the effect of increasing polarized moonlight in the first and last quarter on the flying activity of pests. Catching quantity depend on the connection with the collecting distance when is the greatest of collection distance.